There are many buildings, facilities, sites and locations that require electric power and yet do not have fixed electric power distribution systems. There are also many sites and locations having power distribution needs that vary with time. Typically, the electric power requirements in such circumstances are provided by a portable power distribution facility that can be easily installed on a temporary basis, configured and reconfigured to any desired network of main power feed, trunk feeds and branch circuits and conveniently disassembled for storage and/or shipment to other locations. Examples of locations often requiring temporary or portable power distribution systems include motion picture and television production facilities, construction sites, convention and exhibit halls and any areas or locations during times of emergency such as earthquakes and the like.
Lugged cables provide an important component in such portable power distribution systems. Lugged cables comprise heavy, high power conductors having connector ends for coupling components of the power distribution system to one another. The cables are used to distribute power from, e.g., a portable generator to power distribution boxes and cabinets arranged throughout a location requiring power, and for connecting lighting fixtures, motors and other electrical equipment in branch circuits arranged about the power distribution boxes and cabinets.
As should be understood, safety is an important consideration in the design of cables and other components used to build portable or temporary power distribution systems. It is necessary to properly insulate high power cables and equipment from exposure to users and to insure that couplings and connectors are mechanically secure to prevent "live" cables from coming loose and presenting shock hazards. Moreover, over-current protection is also important to disconnect electrical branch circuits from a power source during branch overload or short circuit conditions to prevent shock hazards and fire.
While the prior art has provided important advances in leak tight insulation and secure mechanical couplings for power cables, over-current circuit protection is still a problem in portable and temporary power distribution networks, particularly in branch circuits remote from a portable generator or main power feed cabinet. Connector cables are often manufactured with heavy, insulating, rubber housings at the connector ends of the cable to cover and insulate connections between power cables. In addition, mechanical arrangements are installed at cable connector ends to lock cables to one another for high integrity of mechanical linkages between high power conductors. However, there is still a lack of adequate over-current protection mechanisms that can be easily and conveniently installed throughout the portable power distribution network, e.g., at each branch circuit of the network.
Far too often, the only over-current circuit protection comprises circuit breaker equipment located at a main power distribution panel. Cables provide trunk lines from the main panel to other power distribution boxes and cabinets located throughout the site where the power distribution system is installed. These power distribution boxes and cabinets, in turn, are connected by cables to many individual branch circuits providing power to the electrical equipment being utilized at the particular site. Consequently, an overload or short circuit condition at one of the many branch circuits may not result in a surge of current sufficient enough to activate a circuit breaker at the main panel, yet the overload is serious enough to cause a shock hazard or fire at the location of the branch circuit. Thus, there is a need for a portable over-current protection mechanism that can be conveniently installed at each branch circuit of a portable power distribution system to achieve highly localized over-current protection throughout the system.